Electrical compensating circuit



April 23, 1957 B. A. GLASSMACHER 2,790,093

ELECTRICAL COMPENSATING CIRCUIT H Filed Sept. 7, 1954 2 Sheets-Sheet l IN VEN TOR. Bernard A. G/assmagh er A TTORNE April 1957 B. A. GLASSMACHER 2,790,093

ELECTRICAL COMFENSATING CIRCUIT Filedsept. 7, 1954 2 Sheets-Sheet 2 INVENTOR. Bernard A. G/anmacber ATTORNEY United States Patent ELECTRICAL COMPENSATING CIRCUIT Bernard A. Glassmacher, Columbus, Ohio, assignor to Surface Combustion Corporation, Toledo, Ohio, a corporation of Ohio This invention relates to an electrical compensating cir-- cuit, and more particularly, to a circuit which, when supplied either of two predetermined voltages, will supply two specified voltages, different from one another, across separate pairs of outlet contacts.

In the fields of heating and air conditioning, for example, many installations require 220 volt current for operation of blowers and, perhaps, other components of the system, but 110 volt current for operation of control circuits. Portable units must utilize both voltages, therefore, whether a 110 volt source or a 220 volt source is available. Heretofore it has been common practice in this field to provide duplicate circuits for supplying current to these separate parts of the apparatus. One of such supply circuits is adapted to receive, for example, 110 volt current which it delivers directly to the low voltage part of the apparatus, and which it transforms to, for example, 220 volts and delivers to the high voltage portion of the apparatus. The separate second circuit is adapted to receive 220 volt current, which it delivers directly to the high voltage portion of the apparatus, and which it transforms to 110 volts for delivery to the low voltage portion of the apparatus. In order to connect such portable apparatus it is necessary to ascertain which voltage is available, and then connect the appropriate circuit to the available source, so that there are chances for error in making the connection. Also, the cost and complexity of the apparatus are increased by inclusion at all times of an unused circuit, including a transformer.

The instant invention is based upon the discoveryof a circuit which, when supplied with either of two voltages, 110 volt current or 220 volt current for example, supplies 220 volts to the blowers, or to other high voltage consu ners, and 110 volts to the control circuit or other low voltage consumers.

It is, therefore, an object of the invention to provide an electric circuit adapted for attachment to a line which delivers either a voltage A or a lower voltage B, and to supply, regardless of whether the line voltage is A or B, a higher voltage to high voltage contacts and a lower voltage to low voltage contacts.

It is a further object of the invention to provide a voltage compensating system which supplies approximately E/2 volts to a low voltage circuit and approximately E volts to a high voltage circuit regardless of whether the voltage applied to the compensating circuit is approximately E/ 2 volts or approximately'E volts.

Other objects and advantages will be apparent from the description which follows, reference being had to the attached drawings, in which Fig. 1 is a partially schematic wiring diagram showing one particular compensating circuit according to the invention.

'Fig. 2 is a diagram similar to Fig. 1, showing a preferred embodiment of the invention; and

Fig. 3 is a sectional view showing details of mating male and female plugs represented in Fig. 2.

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Referring now in more detail to the drawings, the specific compensating circuit shown in Fig. 1 includes a transformer indicated generally at 10 and having a first winding 11, a second winding 12, and a core 13. In the specific embodiment of the invention shown the first winding 11 of the transformer 10 is connected to lines 14 and 15. The line 14 is connected through a single throw, single pole, switch 16 having a contact 17 to one side of a suitable male plug 18 which may be connected to supply either volts or 230 volts. The line 15 is connected to a contact 19 of a double throw, single pole switch 20, which is connected to a line 21 that connects to the second side of the plug 18.

The second winding 12' is connected to lines 24 and 25. The line 25 is connected to a contact 26 of the switch 20.

An armature 27 of a relay 28, which, in the specific embodiment shown, is a 230 volt relay, operates the switch 20. The coil of the relay 28 is connected by lines 30 and 31 through the line 14, and the line 21, respectively, to the plug 18.

The switch 16 is a latching type relay biased open by a spring 32, and remains open unless manually closed. A holding coil 33 acting on an armature 9 keeps the switch 16 in a closed position, after the latter is closed manually, so long as about 115 volt A. C. is supplied to a solenoid 33 through lines 34 and 35.

The positions shown for the armature 27 and the switch 2G are those assumed when the voltage supplied to the plug 18 is less than about 220 volts, so that the relay 28 is not actuated. In this position, when 115 volt current is supplied to the plug 18, and the switch 16 is closed manually, this current flows through the line 14, through the first coil 11 acting as a transformer primary, and through the line 15, contact 19, switch arm 20 and line 21. 115 volt current is then supplied between output lines 37 and 38, which are connected, respectively, to the lines 14 and 15, at the ends of the first coil 11. The output lines 37 and 38 can be used to energize, for example, the control system of heating or air conditioning equipment. The second coil 12 is represented as having approximately twice as many turns as the primary coil 11, so that the voltage between the ends of the second coil in the lines 24 and 2 5 is 230 volts, which voltage is supplied between the line 37, to which the line 24 -is connected, and a third output line 40. The voltage available between the lines 37 and 40 can energize, for example, the blowers of heating or air conditioning apparatus. It will be noted that, in this specific embodiment of the invention, the ratio of output voltages between that of the lines 37 and 38 and that of the lines 37 and 40 is 1:2, the same as the ratio of the number of turns in the first coil 11 to the turns in the second coil 12.

t a line voltage of 230 volts is supplied to the plug 18, this voltage passes through the relay 28 and causes the armature 27 to move downwardly to its second position so that the switch 20 makes a connection with the contacts 26. The switch 22! then constitutes an open switch between the lines 15 and 21, and a closed switch between the lines 25 and 21. Current flows through the line 21, switch arm 26, contact 26, and through the line 25, and, when the switch 16 is manually closed, through the line 24 to energize the second winding 12. The transformer 10 then serves as a stepdown transformer so that a voltage of approximately 115 volts, in the specific embodiment of the invention shown, is induced in the first winding 11, and. supplied through the lines 37 and 38, as above described. The lines 37 and 49 continue to supply approximately 230 volts since this voitage appears at the ends of the coil 12 which is now connected as a transformer primary winding. The ratio of the two applied voltages (115 to 230) is the same as the ratio of the number of turns in the first coil 11 to the number of turns in the second coil 12.

The switch 16 acts as a protecting device to prevent even the momentary application of a high voltage to the winding 11, before actuation of the switch 20 by the relay 28. Until the switch 16 is closed manually, neither the coil 11 nor the coil 12 can be energized. The steps in connecting the circuit, therefore, are to energize the plug 18 with either 115 or 230 volts, whereupon the relay 28 positions the switch 20 appropriately, and then to close the switch 16. Since the lines 34 and 35 are connected to the lines 38 and 37, respectively, about 115 volts is supplied to the coil 33 to hold the switch 16 closed so long as the circuit remains energized. As soon as power to the transformer 10 is out 011, however, the switch 16 is moved to the open position by the spring 32, so that even momentary application of 230 volt power to the winding 11 is prevented.

The compensating circuit shown in Fig. 2 includes an auto transformer indicated generally at 41, having a. single winding 42 center tapped by a line 43. Aline 44, common to both sides of the auto transformer is connected directly to pin 45 in a plug indicated generally at 46. The line 43 is connected to a contact 47 of a switch 48, which is connected by a line 49 to a second pin 50 of the plug 46. A line 51 is connected to the line 49 and to one side of the coil of a relay 52. A line 53 is connected between the other side of the coil of the relay 52 and a third pin 54 of the plug 46. A line 55 is connected to the winding 42 opposite its connection to the line 44. A line 56 is connected between the line 55 and a second contact 57 of the switch 48.

In the specific embodiment of the invention shown the relay 52 is a 230 volt relay which assumes the position represented unless a current of substantially 230 volts is applied thereto.

As will be apparent from Fig. 3, the pins 50 and 54 are longer than the pin 45. As a result, when the pins of the plug 46 are inserted in a mating female receptacle indicated generally at 58, the pins 50 and 54 make contact with receptacles 59 and 60 to energize the lines 49 and 53 before the pin 45 makes contact with a receptacle 61, which is electrically connected to the receptacle 60. The relay 52 is, therefore, energized before current is applied to the line 44. As a result, the switch 48 assumes the appropriate position by cooperation between an armature 62 of the relay 52 and the plug 46 and receptacle 58 before any current is applied to the auto transformer. Lines 63 and 64 of the receptacle 58 can be connected either to a 230 or to a 115 volt power source; the cooperr ative relationship between the plug 46, receptacle 58 and the relay 52 automatically adapts the circuit so that the voltage is applied to the proper side of the auto transformer. When the current applied to the lines 63 and 64 is 110 volts, the switch 48 remains in the position shown and the applied voltage is introduced into the auto transformer through the lines 43 and 44. The applied line voltage is then available between the line 44 and a line 65 connected to the line 43. Approximately 230 volts is available by virtue of transformation between the lines 44 and 55.

When the current applied to the lines 63 and 64 is 230 volts, the armature 62 of the relay 52 lowers the switch 48 into closed relationship with the contact 57, as soon as the pins 50 and 54 are introduced into the receptacles 59 and 60. When the pin 45 is introduced into the receptacle 61 so that the line 44 is energized the auto transformer acts as a step down transformer so that approximately 115 volts are available by virtue of transformation between lines 44 and 65, While the applied line voltage is available between the lines 44 and 55.

It will be apparent that various changes and modifications can be made from the specific details shown in the drawing and explained in the discussion concerned therewith without departing from the spirit of the attached claims. It will also be apparent that the specific voltages discussed are exemplary only, and the relays 28, 16 and 52 and their armatures 27, 9 and 62, respectively, can be replaced with any of several equivalent devices. In essence, a voltage compensating circuit according to the invention comprises a transformer having first and sec ond windings, one of which windings can constitute a part of the other, as in the case of an auto transformer, of a given ratio less than one; a power source which supplies one of two voltages which differ from one another in the same ratio; switch means operative in a first position to connect the first winding as a primary to the power source, and operative in a second position to connect the second winding as a primary to the power source; means operable for setting the switch means in the first position in response to the lower of the voltages and in the second position in response to the higher of the voltages, and output connections to the first and second transformer windings.

What I claim is:

l. A voltage compensating circuit comprising a transformer having a first and second winding of a given ratio less than one, a power source having one of two voltages which clitfer with respect to each other in said given ratio, a relay having an energizing coil connected to said power source, and switch means operated by said relay to establish connections whereby said first transformer winding operates as a primary winding when said power source is at its lower voltage and said second transformer winding operates as a primary winding when said power source is at its higher voltage and output connections to said first and second transformer windings.

2. A voltage compensating circuit comprising a transformer having a first and second winding of a given ratio less than one, a power source having one of two voltages which differ with respect to each other in said given ratio, switch means operative in a first position to connect said first winding as a primary to said power source, and operative in a second position to connect said second winding as a primary to said power source, means operable for setting said switch means in the first position in response to the lower of said voltages and in the second position in response to the higher of said voltages, and output connections to said first and second transformer windings.

3. A voltage compensating circuit comprising a transformer having a first and second winding of a given ratio less than one, a power source having one of two voltages which, differ with respect to each other in said given ratio, switch means operative in a first position to connect said first winding as a primary to said power source, and operative in a second position to connect said second winding as a primary to said power source, electrical means operable for setting said switch means in the first position in response to the lower of said voltages and in the second position in response to the higher of said voltages, means for preventing the energizing of either of said windings until after said electrical means has been energized, and output connections to said first and second transformer windings.

4. A voltage compensating circuit as claimed in claim 3 wherein the transformer is an auto transformer.

References Cited in the file of this patent UNITED STATES PATENTS 1,812,712 Pfeifer June 30, 1931 2,157,417 Kneisley May 9, 1939 2,251,494 Newton Aug. 5, 1941 

